A low-voltage switching device includes a contacting unit including a stationary contact and a movable contact movable between a rest position and a working position, wherein arcs are formed between the contacts when disconnection of the contacts, that means when the movable contact is disconnected from the stationary contact. To extinguish the arcs, an arc-extinguishing chamber is provided and arranged to enclose the contacting unit. The arc-extinguishing chamber may have a plurality of U-shaped arc extinguishing plates arranged for splitting, guiding and cooling the arc formed between the contacts. To improve the breaking/disconnection capacity of the switching device, the arc-extinguishing chamber must provide an effectively attraction of an arising arc from the contact surfaces into the arc extinction chamber. When an arc is attracted into the arc-extinguishing chamber, it is further divided into several shorter arcs by the arc-extinguishing plates, which increases the voltage drop over the separated contacts and consequently breaks the electrical current. To attract the arc into the arc-distinguishing chamber, a force is needed to act on the arc. In order to achieve this force, the arms of U-shaped arc extinguishing plates is arranged to affect the magnetic field created by the arc so that the force acting on the arc increase. It is desirable that the arc will be attracted straightly into the arc-extinguishing chamber to prevent re-ignition directly between the contacts. At the meanwhile, it is desired that the arcs will not damage the arms, which drastically decrease the breaking capacity.
An EP patent EP 1 103 996 B1 discloses a switching device having a bridge of two movable contacts with corresponding arc extinguishing plates and guidance means provided for receiving and guiding arms/ends of the arc extinguishing plates. These guidance means are also capable of insulating the arc extinguishing plates from the movable contacts and of reinforcing the side wall of the switching device.